ATHENS — Constantine Mitsotakis, a former conservative prime minister who engaged in fierce confrontations with Greece’s liberal and socialist parties and tried to loosen state control of the economy in a 60-year political career, died on Monday. He was 98.
His family announced his death but did not say where he died.
Mr. Mitsotakis was prime minister from 1990 to 1993, a relatively brief departure from two decades of dominance by his Socialist rivals. He retired from active politics in 2004 but remained honorary chairman of the center-right New Democracy party.
He was credited with starting unpopular free-market policies, which were quietly continued by later governments, and with improving relations with Turkey. But he was often considered a divisive figure in a country struggling to escape its volatile political history.
Mr. Mitsotakis was born in the port of Hania on the Greek island of Crete on Oct. 18, 1918. He was a nephew of the liberal statesman and prime minister Eleftherios Venizelos, Greece’s most prominent political figure of the early 20th century.
Mr. Mitsotakis was elected to Parliament as a member of the liberal party in 1946, and he served in several cabinet posts, including finance minister, in liberal governments in 1951 through 1952 and 1963 through 1965.
But in 1965, he led a group of dissidents in abandoning George Papandreou’s liberal Center Union government after it had clashed with King Constantine II over control of the military. Most liberal critics never forgave Mr. Mitsotakis for that decision. Even now the group’s action is referred to in Greece as the “apostasy.”
The meteoric rise of Andreas Papandreou, George’s son and an American-educated economist who had returned to Greece in the early 1960s, was widely seen as a factor in Mr. Mitsotakis’ split with the party.
The resulting political crisis and nearly two years of unstable government helped prompt a group of army colonels to stage a coup in 1967, beginning a seven-year dictatorship.
Mr. Mitsotakis, with other politicians, was immediately arrested and later lived in exile in Paris until shortly before the junta collapsed in 1974.
He re-entered Parliament in 1977 at the head of the small Neoliberal Party. The next year he joined the governing New Democracy party, serving as finance minister, then as foreign minister. He became the party’s leader in 1984 while the conservatives were in opposition.
Mr. Mitsotakis emerged as the main adversary of Andreas Papandreou, who had founded the Panhellenic Socialist Movement in 1974 rather than lead his father’s old party. Mr. Papandreou defeated the conservatives in a landslide in 1981. Andreas Papandreou’s son, George, became prime minister in 2009.
Friends and opponents alike jokingly referred to Mr. Mitsotakis in the 1980s as the conservatives’ “anti-Andreas.” Even old-time conservative barons, many of whom considered Mr. Mitsotakis an interloper and never fully accepted him as one of their own, thought he was the only one who could successfully confront Andreas Papandreou, a gifted orator.
Both leaders ran lavish election campaigns that brought hundreds of thousands of supporters to Athens to attend mammoth flag-waving rallies.
Mr. Mitsotakis narrowly won election in 1990 after the Socialists became entangled in a financial scandal. His administration was marked by a dispute with neighboring Macedonia over that newly independent country’s name, and by large union and student protests against his free-market and education policies.
Leading with a one-seat majority in Parliament, his government was brought down by conservative dissenters in 1993, condemning New Democracy to spend the next 11 years in opposition.
Their leader, Antonis Samaras, was eventually welcomed back into the party and defeated Dora Bakoyannis, Mr. Mitsotakis’ eldest daughter, in a leadership contest after the conservatives lost the 2009 election. Mr. Samaras was prime minister from 2012 to 2015, in coalition with the Socialists.
Ms. Bakoyannis was mayor of Athens during the 2004 Olympic Games and foreign minister in a New Democracy government from 2006 to 2009. Her husband, Pavlos Bakoyannis, a conservative politician, was shot to death in 1989 by members of the far-left Greek terrorist group Nov. 17.
After his resignation as party leader, Mr. Mitsotakis urged governments to make bolder steps toward a freer market and led an unsuccessful effort to have Greece’s president elected directly by the people. He denied he coveted the country’s top job.
Mr. Mitsotakis, who enjoyed good health until late in life, lived long enough to see his youngest child and only son, Kyriakos, elected leader of New Democracy in January 2016.
Besides his son and Ms. Bakoyannis, he is survived by two other daughters, Alexandra Mitsotakis Gourdain and Katerina Mitsotakis; and several grandchildren and great-grandchildren. His wife, Marika, died in 2012.